It is widely known to attempt to deploy complex circuits for electrostatic discharge protection (ESD) protection with various electronic circuitry and sophisticated electronic devices. It also known that even with sophisticated ESD circuitry, in many situations, an ESD protection circuit does not act rapidly enough to prevent electrostatic damage to the circuitry of interest. Oftentimes there are resistance/voltage disparities that can be too high in most electrostatic discharge protection circuits causing them to lose protection on high voltage ESD spikes. In the other extreme, some protection circuits do not function well at low voltages.
Consumers are often unclear about the dangers or effects of ESD and do not always realize that static charge may build up on the USB device. Occasionally, when a static charge builds up on a USB device which is then plugged into a USB socket, the static charge is transmitted to signal lines of the socket, plug or connector, which can then damage the USB device, an attached computer board, or any other electronic or silicon device connected thereto.
As a result, consumers are often perplexed when their USB peripherals, devices, ports, hubs, plugs, sockets, links and any other equipment having or being capable of being placed into operative communications with a USB plug or port (hereinafter used collectively as “USB device”), is damaged after being subject to discharge or damage from an ESD shock (“ESD hit”). In part, part of this confusion arises because as there is no visual damage to the affected device(s). Another similar result can be that of “latch up” which results in creating a low-impedance path between the power signal of an electronic component inadvertently that triggers a parasitic device to acts as a short circuit; often times the latch up will lead to improper function of the electronic device (e.g. USB device) or even its destruction due to a resulting overcurrent.
A “USB device” may further include and is not limited to any of the following, each being hot-swappable and/or having a USB connector or connection capability: Printer, Scanner, Mouse, Joystick, Flight yoke, Digital camera, Webcam, Cellular phone, Scientific data acquisition device, Computer, Computer System, Modem, Speaker, Telephone, Video phone, Storage device, Home appliance, and Network connection. A “USB device” may comprise a Type A connection (which is oriented to head “upstream” towards the computer), a Type B connection (which is oriented to head “downstream” away from the computer and connects to individual devices), a USB socket, or any other connection capable of USB connectivity. “USB connection” or “USB connector” may be used interchangeably and includes a USB plug or USB socket, of any Type or style, powered or unpowered.
FIG. 1 depicts a typical Type A USB connector (110).
FIG. 2 depicts a typical Type B USB connector (210).
FIG. 3 depicts a typical USB socket (310) in a hub (320) configuration.
FIG. 4 depicts a typical Type A USB connector (410) arranged for connection with its USB-paired socket (420).
FIG. 5 depicts a typical USB cable (501) being shielded and comprised of four wires (i.e., signal pins or lines), two of which carry power (510 and 520), wherein 510 typically carries 5 volts and 520 is a ground, and two of which carry data (530 and 540) which are typically twisted pair.
FIG. 6 depicts a typical signal pin configuration (610, 620, 630, 640) for a typical USB connection, wherein each pin is connected to a USB cable wire (not shown), such as those of FIG. 5.
FIG. 7 depicts a typical thumb drive as a USB device (710).
However, the use of external metal shielding surrounding a USB device's plastic housing (often near the USB connector), which in turn surrounds the two data lines and two power lines of the USB connector, has been ineffective and may inadvertently cause the exposed external metal shield to attract additional ESD charges even after being operatively connected.
Unfortunately, these external efforts and those of the complex ESD circuitry are often too costly, inadequate and can be too obtrusive to be used with USB devices; additionally, these efforts often do not satisfy spatial constraints at connection ports which have been further limiting dimensional footprints of many USB devices as computers and peripherals continue to become smaller in size.
Accordingly, what is needed is a method and apparatus for providing ESD protection to USB devices that is easily implemented, compatible with all (or most) existing technologies, is cost effective, and is of minimal dimensional impact to the USB device.